Eric Bielefeld wrote: > Really? I always thought the 3380s and 3390s were CKD device also
Yes, really. Seymour J is right, as hard as that might be to believe. These drives are, under the covers, really FBA devices. Externally, however, they are CKD devices (because you use the standard CKD CCW command set in channel programs to read from and write to them). So they are both. But, depending on your mindset, one could argue that they are one and not the other. Whatever. In my mind they are both. The distinction is actually important, and in some cases, critical -- more than just an issue of seeming external compatibility. Calculating track capacity on pseudo-CKD DASD requires use of a slightly different algorithm, one that takes into account the underlying "cell" structure of the device. When the 3380 first came along, anybody that had such code had to update their embedded track capacity calculation code to be aware of the new "cell" scheme (as it was then designated by IBM). Today one normally uses a service provided by MVS to do this, but it was not available on MVS/SP when the 3380 (finally) did get shipped. -- WB ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
